R5F21238DFP#U0 Renesas Electronics America, R5F21238DFP#U0 Datasheet - Page 434

• Manufacturer Part Number: R5F21238DFP#U0
• Description: IC R8C/23 MCU FLASH 48-LQFP
• Manufacturer: Renesas Electronics America
• Series: R8C/2x/23r

Specifications of R5F21238DFP#U0

• Core Size: 16/32-Bit
• Program Memory Size: 64KB (64K x 8)
• Peripherals: POR, Voltage Detect, WDT
• Core Processor: R8C
• Speed: 20MHz
• Connectivity: CAN, I²C, LIN, SIO, SSU, UART/USART
• Number Of I /o: 41
• Program Memory Type: FLASH
• Ram Size: 3K x 8
• Voltage - Supply (vcc/vdd): 2.7 V ~ 5.5 V
• Data Converters: A/D 12x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 48-LQFP
• No. Of I/o's: 41
• Ram Memory Size: 3KB
• Cpu Speed: 20MHz
• No. Of Timers: 4
• Digital Ic Case Style: LQFP
• Embedded Interface Type: CAN, I2C, UART
• Rohs Compliant: Yes
• Cpu Family: R8C
• Device Core Size: 16b
• Frequency (max): 20MHz
• Interface Type: I2C/UART
• Total Internal Ram Size: 3KB
• # I/os (max): 41
• Number Of Timers - General Purpose: 5
• Operating Supply Voltage (typ): 3.3/5V
• Operating Supply Voltage (max): 5.5V
• Operating Supply Voltage (min): 3V
• On-chip Adc: 12-chx10-bit
• Instruction Set Architecture: CISC
• Operating Temp Range: -40C to 85C
• Operating Temperature Classification: Industrial
• Mounting: Surface Mount
• Pin Count: 48
• Package Type: LQFP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With: RCDK8C - KIT DEV EVAL FOR CAN R8C/23R0K521237S000BE - KIT DEV RSK R8C/23R0E521237CPE00 - EMULATOR COMPACT R8C/20/21/22/23
• Eeprom Size: -
• Lead Free Status / Rohs Status: Compliant

R8C/22 Group, R8C/23 Group
Rev.2.00 Aug 20, 2008
REJ09B0251-0200
19.6
Figure 19.11
To carry out A/D conversion properly, charging the internal capacitor C shown in Figure 19.11 has to be completed
within a specified period of time. T (sampling time) as the specified time. Let output impedance of sensor
equivalent circuit be R0, internal resistance of microcomputer be R, precision (error) of the A/D converter be X,
and the resolution of A/D converter be Y (Y is 1024 in the 10-bit mode, and 256 in the 8-bit mode).
Figure 19.11 shows Analog Input Pin and External Sensor Equivalent Circuit. When the difference between VIN
and VC becomes 0.1LSB, we find impedance R0 when voltage between pins VC changes from 0 to VIN (0.1/1024)
VIN in time T. (0.1/1024) means that A/D precision drop due to insufficient capacitor charge is held to 0.1LSB at
time of A/D conversion in the 10-bit mode. Actual error however is the value of absolute precision added to
0.1LSB.
When f(XIN) = 10 MHz, T = 0.25 µs in the A/D conversion mode without sample & hold. Output impedance R0
for sufficiently charging capacitor C within time T is determined as follows.
Thus, the allowable output impedance of the sensor equivalent circuit, making the precision (error) 0.1LSB or less,
is approximately 1.7 kΩ maximum.
Output Impedance of Sensor Under A/D Conversion
VC is generally VC = VIN 1 - e
And when t = T, VC = VIN -
Hence, R0 = -
T = 0.25 µs, R = 2.8 kΩ, C = 6.0 pF, X = 0.1, and Y = 1024. Hence,
R0 = -
Analog Input Pin and External Sensor Equivalent Circuit
6.0 × 10
0.25 × 10
C 1n
-12
Page 412 of 501
-
e
T
C(R0 + R)
-
NOTE:
1n
C(R0 + R)
X
Y
-6
Sensor equivalent circuit
1024
1. The capacity of the terminal is assumed to be 4.5 pF
0.1
1
-R
1
VIN
- 2.8 × 10
T
X
Y
T
= 1n
VIN = VIN 1 -
=
-
C(R0 + R)
X
Y
X
Y
R0
1
3
~ ~
1.7 × 10
t
X
Y
MCU
3
R(2.8kΩ)
C(6.0pF)
VC
19. A/D Converter